1. Field of the Invention
This invention relates to the measurement of the discrete hydraulic head in aquifers within geologic media adjacent to a borehole, in conjunction with transmissivity data previously measured for the same medium.
2. Background Art
A “borehole” is a hole, e.g., a drilled shaft, into the Earth's subsurface. The hydraulic conductivity profiling techniques described in my U.S. Pat. Nos. 6,910,374 and 7,281,422 have been used in over 200 boreholes since 2007. These two patents, whose complete teachings are hereby incorporated by reference, describe the hydraulic transmissivity profiling technique which carefully measures the eversion of a flexible borehole liner into an open stable borehole. From those measurements is obtained a monotonically decreasing liner velocity, from which is calculated a continuous transmissivity distribution in the geologic formation penetrated by the borehole. The method of these patents assumes a constant head distribution in the formation if no other information is available. The flow in the geologic formation, however, is dependent not only on the transmissivity but also on the head in the formation. In particular, the vertical transport of contaminants and the recharge of subsurface aquifers depend upon the definition of the vertical transmissivity and the vertical gradient. The definition of aquitards is particularly important to the understanding of the migration of ground water contaminants.
With the foregoing background, the presently disclosed invention was developed. The invention described hereafter helps to determine and define the presence of aquitards, and to assist in the definition of those intervals which may then be best monitored with a multi-level sampling system for water quality and long term vertical gradient definition.